Re: [PATCH v7 6/7] sched: replace capacity_factor by usage

From: Peter Zijlstra
Date: Thu Oct 09 2014 - 08:17:11 EST


On Tue, Oct 07, 2014 at 02:13:36PM +0200, Vincent Guittot wrote:
> +static inline bool
> +group_has_capacity(struct lb_env *env, struct sg_lb_stats *sgs)
> {
> + if ((sgs->group_capacity * 100) >
> + (sgs->group_usage * env->sd->imbalance_pct))
> + return true;

Why the imb_pct there? We're looking for 100% utilization, not 130 or
whatnot, right?

> + if (sgs->sum_nr_running < sgs->group_weight)
> + return true;

With the code as it stands, this is the cheaper test (no mults) so why
is it second?

> + return false;
> +}
>
> +static inline bool
> +group_is_overloaded(struct lb_env *env, struct sg_lb_stats *sgs)
> +{
> + if (sgs->sum_nr_running <= sgs->group_weight)
> + return false;
> +
> + if ((sgs->group_capacity * 100) <
> + (sgs->group_usage * env->sd->imbalance_pct))
> + return true;
>
> + return false;
> }

Same thing here wrt imb_pct
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